Tailoring the band gap of α2-graphyne through functionalization with carbene groups: a density functional theory study

Similar to graphene, the absence of band gap limits applications of the recently proposed α2-graphyne sheet. We have investigated tuning the energy band of α2-graphyne through functionalization with carbene groups. The effect of carbene group CR2 (R = Cl, H, CN, CH3, and NO2) on the structural and electronic properties of α2-graphyne is studied by density functional theory study. The binding energy, charge transfer, equilibrium geometries, electronic band structures, and density of states of pure and functionalized α2-graphyne sheets are calculated. It is found that the chemical functionalization of α2-graphyne with carbene groups causes the structural deformation and opens the band gap. The energy band gap of α2-graphyne increases by 0.48 eV as the concentration of carbene groups varies. Our results indicate that chemical functionalization is an effective way to tune the electronic properties of α2-graphyne.